Field of the Invention
The present invention relates to a method of controlling a sewing machine, in particular a sewing machine comprising an axially movable needle, a device for driving the needle with an alternating axial movement, a mechanism for controlling the relative displacement, in translation, of the needle and the material to be sewn, a loop pick-up and its control device, and means for controlling in synchronism said mechanisms and the device, adapted in such a manner as to sew on the material designs or patterns each formed by a plurality of blocks of stitches and at least a portion of the shape of each of which embodies at least one series of two adjacent stitches resulting from a relative displacement of the cloth and the needle, of different amplitude and/or orientation from stitch to stitch. The machine further comprises a control unit for the control means and the device enabling respective increase or reduction in the base length of a design or pattern while keeping the density of the stitches sewn constant.
The invention also relates to a computerized sewing machine, comprising
first means for controlling alternating axial movement of a needle to penetrate into the material to be sewn, and a loop pick-up adapted to co-operate with the needle to form a sewing stitch, PA1 second means for controlling the relative displacements of the needle and the material to be sewn in two orthogonal directions of specific amplitude in each direction, PA1 at least one electronic memory for storage of sewing instructions corresponding to various designs or patterns to be sewn, these instructions being capable of being selectively and sequentially read to effect control of said second means, PA1 first units for selection of said designs or patterns, PA1 a microprocessor co-operating with said memory to read from it sewing instructions for any design selected and to control as a result the second control means, PA1 third means operating on the microprocessor, based on instructions stored in the memory, to control the formation of designs or patterns of different length from those corresponding to said instructions. PA1 second units for selection of the variation in length desired in the formation of any preselected design or pattern. PA1 B=0, 1, 2 . . . N-1 is a number characteristic of the position occupied by each block of stitches of a basic design of "n" blocks, between the beginning (position o) and the end (position n-1) of this design; PA1 B.sub.N is the absolute value of B calculated in a numeric system of base N; PA1 K is the ratio between the total length of the design and the value of the unit increment; and PA1 K.sub.N is the absolute value of K calculated in a numeric system of base N. PA1 first means for controlling, on the one hand, alternating axial movement of a needle with a view to making it penetrate into material to be sewn, and on the other hand, a loop pick-up adapted to co-operate with the needle with a view to effecting formation of a sewing stitch. PA1 second means for controlling relative displacements of the needle and the material to be sewn in two orthogonal directions with a specific amplitude in each direction, PA1 at least one electronic memory for storing sewing instructions corresponding to various designs to be sewn, these instructions being capable of being read sequentially and selectively to effect control of said second means, PA1 first selection units for said designs, PA1 a microprocessor for co-operating with said memory to read from it sewing instructions for any selected design and to control as a consequence the second control means, PA1 third means for operating on the microprocessor, based on instructions stored in the memory, to control execution of designs of a length different from that corresponding to said instructions, and PA1 second units for selection of the variation desired in the length to be implemented for any preselected design, wherein said third means embodies, stored in the memory, on the one hand, a first sequence of computerized instructions causing the microprocessor to read repeatedly instructions for sewing at least certain from among the blocks of stitches comprised in the selected design as memorised in such a manner as to obtain a corresponding repetition of the sewing of these blocks within the design of modified length as a function of the variation selected by actuation of said second units, and, on the other hand, at least a second sequence of computerized instructions setting the number of times that each block belonging to the original design should be sewn, in the modified design, as well as the positioning of the block within the modified design, the procedure being effected in such a manner that the elongated design sewn on said material has the modified length required while retaining a general shape resembling that of the basic design stored in the memory and from which it is derived.